Oh, I should have mentioned that the majority of it is growing on rubber mulch, which I found interesting when it started.
There is also a lot growing in the gap I clear next to the rocks bordering the stonecrop and that is growing on bare earth. You can see that in the 2nd photo, to the right of the row of rocks.
Something else to note is that this is on the north side of the house and gets full sun from midday on.
Predating Galileo even.